Finite element modelling of implant designs and cortical bone thickness on stress distribution in maxillary type IV bone.

The aims of this study were to examine the effect of implant neck design and cortical bone thickness using 3D finite element analysis and to analyse the stability of clinical evidence based on micromotion and principal stress. Four commercial dental implants for a type IV bone and maxillary segments were created. Various parameters were considered, including the osseointegration condition, loading direction and cortical bone thickness. Micromotion and principal stresses were used to evaluate the failure of osseointegration and bone overloading, respectively. It was found that the maximum stress of the peri-implant bone decreased as cortical bone thickness increased. The micromotion level in full osseointegration is less than that in non-osseointegration and it also decreases as cortical bone thickness increases. The cortical bone thickness should be measured before surgery to help select a proper implant. In the early stage of implantation, the horizontal loading component induces stress concentration in bone around the implant neck more easily than does the vertical loading component, and this may result in crestal bone loss.

Follow up of neonata hypoxic ischemic encephalopathy and ventricular dilatation / 实用儿科临床杂志

Objective To investigate the prognostic sequelae in neontes with hypoxic-ischemic encephalopathy (HIE) and ven-tricnlar dilatation.Methods Seventy-six full term newborns infants with HIE were followed up at the age from 3 to 19 months after therapy. Twenty-five infants among them were followed up by telephone in the epidemic period of SARS.Results Among 76 infants of 88 newborn infants with HIE(84.6%), 73 infants were normal (96.1% ). 1 infant had cerebral palsy (1.3%), 2 infants died (2.6 %).Among 39 cases with mild HIE, none of them had cerebral sequelae; among moderate HIE. 1 infant had cerebral palsy (2.9%) 1 infant died (2. 9 %), interlenkin-4 among severe HIE 50 % died (P00.5 The poor outcome of HIE in those infants were related to intrauterine growth retardation,severe birth asphyxia;and inadequate treatment.Cranial ultra-sonography of 49 infants were done on follow-up,and 12 of them (24.5 % ) had ventricular dilatations, which appeared after birth with 6 infants. Others occurred on follow-up with 1 infant had cerobral palsy,all ventricular dilatations recovered to normal at 12- 19 months except the cerebral palsy.Conclusions The poor outcome of HIE depends on the infants with intranterine growth relarda-tion,severe birth asphyxia and inadequate treatment.The prognosis of transient ventrealar ddatation are good except cerebral palsy.J Appl Clin pediatr,2004,19(12) : 1045- 1047